Liquid crystal display device and method for manufacturing LGP positioning block thereof

ABSTRACT

A method for manufacturing a light guide plate (LGP) positioning block thereof includes providing a positioning block body of a LGP positioning block and filling and sealing a liquid in a receiving compartment formed in the interior of the positioning block body. The liquid is expandable with a drop of temperature so as to increase a volume thereof and thus enlarge a size of the positioning block body through elasticity of the positioning block body. In this way, the LGP positioning block is adjustable with the variation of the surrounding temperature so as to achieve effective positioning of the light guide plate and providing high reliability of a liquid crystal display device including the light guide plate.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of co-pending patent application Ser.No. 15/607,575 filed on May 29, 2017, which is a divisional applicationof patent application Ser. No. 14/429,067 filed on Mar. 18, 2015, nowU.S. Pat. No. 9,726,814, which is a national stage of PCT ApplicationNo. PCT/CN2015/072561, filed on Feb. 9, 2015, claiming foreign priorityof Chinese Patent Application No. 201410842588.5, filed on Dec. 30,2014.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to the field of displaying technology, andin particular to a liquid crystal display device and a method formanufacturing a light guide plate (LGP) positioning block thereof.

2. The Related Arts

Liquid crystal displays (LCDs) have a variety of advantages, such asthin device body, low power consumption, and being free of radiation,and are thus used widely, such as mobile phones, personal digitalassistants (PDAs), digital cameras, computer monitors, and notebookcomputer screens.

Most of the LCDs that are currently available in the market arebacklighting LCDs, which comprise an enclosure, a liquid crystal panelarranged in the enclosure, and a backlight module mounted in theenclosure. Since the liquid crystal panel is not self-luminous, lightsupplied from the backlight module is necessary for normally displayingan image. Thus, the backlight module is one of the key components of aliquid crystal display. The backlight modules can be classified as aside-edge backlight module and a direct backlight module, according tothe site where light gets incident. The direct backlight modulecomprises a light source, such as a cold cathode fluorescent lamp (CCFL)or a light-emitting diode (LED), which is arranged at the backside ofthe liquid crystal panel to directly form a planar light source suppliedto the liquid crystal panel. The side-edge backlight module comprises anLED light bar, serving as a backlight source, which is arranged at anedge of a backplane to be located rearward of one side of the liquidcrystal panel. The LED light bar emits light that enters a light guideplate (LGP) through a light incident face at one side of the light guideplate and is projected out of a light emergence face of the light guideplate, after being reflected and diffused, to pass through an optic filmassembly so as to form a planar light source for the liquid crystalpanel.

The LGP is one of the important components of a liquid crystal displayand is often made of poly(methyl methacrylate) (PMMA), which is alsoreferred to as “organic glass” and has the property of thermalexpansion. When a liquid crystal display is operating in a hightemperature, the LGP gets expanded; and for operation in a lowtemperature, the LGP contracts. The size difference between expandingand contracting might as large as millimeters. On the other hand,positional accuracy between the LGP and the backlight source affects, toa great extent, the image style of the liquid crystal display.

FIG. 1 is an exploded view showing a conventional liquid crystal displaydevice and FIG. 2 is a top plan view showing a backlight module of theconventional liquid crystal display device. With reference to FIGS. 1and 2, the conventional liquid crystal display device comprises abacklight module 10 that is composed of a backplane 100, alight-emitting diode (LED) light bar 200, a light guide plate 300, andan optic film assembly 400, a mold frame 500 arranged on the backlightmodule 10, a liquid crystal panel 600 arranged on the mold frame 500,and a bezel 700 arranged on the liquid crystal panel 600. The lightguide plate 300 comprises positioning posts 800 arranged adjacent to alight-entrance side of the LED light bar 200 to maintain a lightcoupling distance between the light guide plate 300 and the LED lightbar 200, while elastic positioning blocks 900 are arranged at the sideof the light guide plate 300 that is distant from the LED light bar 200to achieve positioning.

As shown in FIG. 3, in a normal temperature, a proper gap is presentbetween the side of the light guide plate 300 that is distant from theLED light bar 200 and the positioning blocks 900 to facilitate assemblyand accommodate manufacturing tolerances.

As shown in FIG. 4, when the liquid crystal display device is in a hightemperature, the light guide plate 300 that is heated and thus expandedgets into contact with the positioning blocks 900. Since the positioningblocks 900 are made of a solid elastic material and thus possesselasticity, they can absorb the increased size of the light guide plate300 caused by expansion so as to maintain stable and tight engagementbetween the light guide plate 300 and the positioning blocks 900.

However, as shown in FIG. 5, when the liquid crystal display device isin a low temperature, the light guide plate 300 is cooled and getscontracted so that the gap between the light guide plate 300 and thepositioning blocks 900 is enlarged. Under this condition, thepositioning blocks 900 do not provide the function of effectivepositioning so that the light guide plate 300 may readily separate andbreak due to actions caused by vibrations and impacts.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystaldisplay device, which has light guide plate (LGP) positioning block thatis adjustable with variation of the surrounding temperature so as toachieve effective positioning of an LGP, thereby providing the liquidcrystal display device with high reliability and stable taste ofdisplayed images.

Another object of the present invention is to provide a method formanufacturing an LGP positioning block of a liquid crystal displaydevice, wherein an LGP positioning block manufactured with such a methodis adjustable with variation of the surrounding temperature to achieveeffective positioning of an LGP.

To achieve the above objects, the present invention provides a liquidcrystal display device, which comprises a backlight module, a mold framearranged on the backlight module, a liquid crystal panel arranged on themold frame, and a bezel arranged on the liquid crystal panel;

wherein the backlight module comprises a backplane, a light-emittingdiode (LED) light bar arranged in the backplane, a light guide plate(LPG) arranged in the backplane, an optic film assembly arranged on thelight guide plate, and a positioning post and an LGP positioning blockthat position the light guide plate; and

the LGP positioning block comprises a positioning block body and liquidhermetically sealed inside the positioning block body and thepositioning block body possesses elasticity;

whereby in a low temperature, the liquid gets condensed and expanded toenlarge a size of the positioning block body to compensate sizereduction of the light guide plate caused by cooling; and in a hightemperature, the elasticity of the positioning block body absorbs sizeexpansion of the light guide plate caused by heating.

The backplane comprises a bottom board and a side board perpendicularlyconnected to the bottom board, the LED light bar being mounted to theside board, the light guide plate comprising a light-entrance side and anon-light-entrance side distant from the light-entrance side, a lightemission surface of the LED light bar opposing the light-entrance sideof the light guide plate; and

the positioning post is arranged at a location adjacent to thelight-entrance side of the light guide plate to maintain a lightcoupling distance between the light guide plate and the LED light barand the LGP positioning block is arranged on the bottom board betweenthe side board and the LGP non-light-entrance side.

The number of the positioning post used is two and the two positioningposts are arranged adjacent to the light-entrance side of the lightguide plate and are opposite to each other; and the number of the LGPpositioning block used is two and the two LGP positioning blocks arearranged opposite to each other and respectively set at corners of theLGP non-light-entrance side.

The positioning block body comprises a sealing trough formed byrecessing a surface thereof, a passageway in communication with thesealing trough and extending into the interior of the positioning blockbody, and a receiving compartment in communication with the passagewayand formed in the interior of the positioning block body; and the liquidis filled in the receiving compartment and the passageway and thesealing trough seals the liquid.

The sealing trough receives sealing adhesive filled therein and thesealing adhesive seals the liquid.

The liquid comprises distilled water.

The positioning block body is made of a material of rubber.

The present invention also provides a method for manufacturing an LGPpositioning block of a liquid crystal display device, which comprisesthe following steps:

(1) providing a positioning block body;

wherein the positioning block body possesses elasticity and comprises asealing trough formed by recessing a surface thereof, a passageway incommunication with the sealing trough and extending into the interior ofthe positioning block body, and a receiving compartment in communicationwith the passageway and formed in the interior of the positioning blockbody;

(2) providing liquid and filling the liquid in the passageway and thereceiving compartment;

(3) applying sealing adhesive in the sealing trough; and

(4) leveling and solidifying the sealing adhesive so that the sealingadhesive seals the liquid in the positioning block body to therebycomplete the manufacture of the LGP positioning block.

The liquid comprises distilled water.

The positioning block body is made of a material of rubber.

The present invention further provides a method for manufacturing an LGPpositioning block of a liquid crystal display device, which comprisesthe following steps:

(1) providing a positioning block body;

wherein the positioning block body possesses elasticity and comprises asealing trough formed by recessing a surface thereof, a passageway incommunication with the sealing trough and extending into the interior ofthe positioning block body, and a receiving compartment in communicationwith the passageway and formed in the interior of the positioning blockbody;

(2) providing liquid and filling the liquid in the passageway and thereceiving compartment;

(3) applying sealing adhesive in the sealing trough; and

(4) leveling and solidifying the sealing adhesive so that the sealingadhesive seals the liquid in the positioning block body to therebycomplete the manufacture of the LGP positioning block;

wherein the liquid comprises distilled water; and

wherein the positioning block body is made of a material of rubber.

The efficacy of the present invention is that the present inventionprovides a liquid crystal display device, which comprises an LGPpositioning block that comprises an elastic positioning block body andliquid hermetically sealed in the interior of the positioning blockbody. In a low temperature, the liquid gets condensed and expanded so asto enlarge the size of the positioning block body to compensate the sizereduction of the light guide plate due to contraction caused by cooling;and in a high temperature, the elasticity of the positioning block bodyabsorbs the size expansion of the light guide plate caused by heating soas to achieve adjustability of the LGP positioning block withtemperature variation and allow for effective positioning of the lightguide plate, thereby providing the liquid crystal display device withhigh reliability and stable taste of displayed images. The presentinvention also provides a method for manufacturing an LGP positioningblock of a liquid crystal display device, in which liquid is firstfilled into the interior of a positioning block body, followed byapplication and solidification of the sealing adhesive to hermeticallyseal the liquid in the interior of the positioning block bod. The LGPpositioning block manufactured with such a method allows foradjustability with variation of the surrounding temperature to achieveeffective positioning of the light guide plate.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solution, as well as other beneficial advantages, of thepresent invention will be apparent from the following detaileddescription of embodiments of the present invention, with reference tothe attached drawing. In the drawing:

FIG. 1 is an exploded view of a conventional liquid crystal displaydevice;

FIG. 2 is a top plan view of a backlight module of the conventionalliquid crystal display device;

FIG. 3 is an enlarged view showing an engagement site between a lightguide plate and a positioning block of FIG. 2 in a normal temperature;

FIG. 4 is an enlarged view showing the engagement site between the lightguide plate and the positioning block of FIG. 2 in a high temperature;

FIG. 5 is an enlarged view showing the engagement site between the lightguide plate and the positioning block of FIG. 2 in a low temperature;

FIG. 6 is a cross-sectional view showing the structure of a liquidcrystal display device according to the present invention in a normaltemperature;

FIG. 7 is a cross-sectional view showing the structure of the liquidcrystal display device according to the present invention in a lowtemperature;

FIG. 8 is a top plan view showing a backlight module of the liquidcrystal display device according to the present invention;

FIG. 9 is a flow chart illustrating a method for manufacturing a lightguide plate positioning block of a liquid crystal display deviceaccording to the present invention;

FIG. 10 is a schematic view illustrating step 1 of the method formanufacturing a light guide plate positioning block of a liquid crystaldisplay device according to the present invention;

FIG. 11 is a schematic view illustrating step 2 of the method formanufacturing a light guide plate positioning block of a liquid crystaldisplay device according to the present invention;

FIG. 12 is a schematic view illustrating step 3 of the method formanufacturing a light guide plate positioning block of a liquid crystaldisplay device according to the present invention; and

FIG. 13 is a schematic view illustrating step 4 of the method formanufacturing a light guide plate positioning block of a liquid crystaldisplay device according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To further expound the technical solution adopted in the presentinvention and the advantages thereof, a detailed description is given toa preferred embodiment of the present invention and the attacheddrawings.

Referring collectively to FIGS. 6-8, firstly, the present inventionprovides a liquid crystal display device. The liquid crystal displaydevice comprises a backlight module 20, a mold frame 5 arranged on thebacklight module 20, a liquid crystal panel 6 arranged on the mold frame5, and a bezel 7 arranged on the liquid crystal panel 6.

The backlight module 20 comprises a backplane 1, a light-emitting diode(LED) light bar 2 arranged in the backplane 1, a light guide plate (LPG)3 arranged in the backplane 1, an optic film assembly 4 arranged on thelight guide plate 3, and a positioning post 8 and an LGP positioningblock 9 that position the light guide plate 3.

Further, the LGP positioning block 9 comprises a positioning block body91 and liquid 93 hermetically sealed inside the positioning block body91. The positioning block body 91 is made of an elastic material, suchas rubber, so that the positioning block body 91 possesses elasticity.The liquid 93 has the characteristics of being condensed when cooleddown and thus increasing the volume thereof, and preferably, the liquid93 is distilled water. Specifically, the positioning block body 91comprises a sealing trough 912 formed by recessing a top surfacethereof, a passageway 913 in communication with the sealing trough 912and extending into the interior of the positioning block body 91, and areceiving compartment 914 in communication with the passageway 913 andformed in the interior of the positioning block body 91. The liquid 93is filled in the receiving compartment 914 and the passageway 913, whilethe sealing trough 912 is filled with sealing adhesive 915 so that theliquid 93 is sealed by the sealing adhesive 915.

The backplane 1 comprises a bottom board 11 and a side board 12perpendicularly connected to the bottom board 11. The LED light bar 2 ismounted to the side board 12. The light guide plate 3 comprises alight-entrance side 31 and a non-light-entrance side 33 distant from thelight-entrance side 31. A light emission surface of the LED light bar 2is opposing the light-entrance side 31 of the light guide plate 3.

The positioning post 8 is arranged at a location adjacent to thelight-entrance side 31 of the light guide plate 3 to maintain a lightcoupling distance between the light guide plate 3 and the LED light bar2. The LGP positioning block 9 is arranged on the bottom board 11between the side board 12 and the LGP non-light-entrance side 33.Specifically, as shown in FIG. 8, the number of the positioning post 8used is two and the two positioning posts 8 are arranged adjacent to thelight-entrance side 31 of the light guide plate 3 and are opposite toeach other. The number of the LGP positioning block 9 used is two andthe two LGP positioning blocks 9 are arranged opposite to each other andrespectively set at corners of the LGP non-light-entrance side 33.

As shown in FIG. 6, when the liquid crystal display device is in anormal temperature of around 25° C., a gap is present between the LGPpositioning block 9 and the light guide plate 3 to facilitate assemblyand to accommodate manufacturing tolerance. As shown in FIG. 7, in a lowtemperature lower than 0° C. down to −20° C., the liquid 93 is cooledand condensed and thus expanded so that the volume thereof is increased,whereby the size of the positioning block body 91 is enlarged tocompensate the reduction of the size of the light guide plate 3 due tocontraction caused by cooling. In a temperature higher than 50° C., suchas a high temperature of 60° C., the liquid 93 may have very littleexpansion so that the elasticity of the positioning block body 91 may besufficient to absorb the size expansion of the light guide plate 3caused by heating. Thus, adjustability of the LGP positioning block 9with temperature variation can be achieved to provide effectivepositioning of the light guide plate 3, thereby achieving highreliability of the liquid crystal display device and stable taste ofdisplayed image.

Referring to FIGS. 9-13, the present invention also provides a methodfor manufacturing the above-described LGP positioning block of theliquid crystal display device, which comprises the following steps:

Step 1: as shown in FIG. 10, providing a positioning block body 91.

The positioning block body 91 is made of an elastic material, such asrubber, so that the positioning block body 91 possesses elasticity.Specifically, the positioning block body 91 comprises a sealing trough912 formed by recessing a top surface thereof, a passageway 913 incommunication with the sealing trough 912 and extending into theinterior of the positioning block body 91, and a receiving compartment914 in communication with the passageway 913 and formed in the interiorof the positioning block body 91.

Step 2: as shown in FIG. 11, providing liquid 93 and filling the liquid93 in the passageway 913 and the receiving compartment 914.

The liquid 93 has the characteristics of being condensed when cooleddown and thus increasing the volume thereof, and preferably, the liquid93 is distilled water.

Step 3: as shown in FIG. 12, applying sealing adhesive 915 in thesealing trough 912.

Step 4: as shown in FIG. 13, leveling and solidifying the sealingadhesive 915 so that the sealing adhesive 915 seals the liquid 93 in thepositioning block body 91 to thereby complete the manufacture of the LGPpositioning block 9.

In the method for manufacturing above-described LGP positioning block ofliquid crystal display device, the liquid 93 is first filled in theinterior of the positioning block body 91, followed by application andsolidification of the sealing adhesive 915 to seal the liquid 93 in theinterior of the positioning block body 91. The LGP positioning block 9manufactured with such a method is characterized in that in a lowtemperature, the liquid 93 is cooled down, condensed, and expanded sothat the volume thereof is increased, making the size of the positioningblock body 91 enlarged to compensate the size reduction of the lightguide plate due to contraction caused by cooling; in a high temperature,the elasticity of the positioning block body 91 absorbs the sizeexpansion of the light guide plate caused by heating so as to achieveadjustability of the LGP positioning block 9 with temperature variationand allow for effective positioning of the light guide plate 3.

In summary, the present invention provides a liquid crystal displaydevice, which comprises an LGP positioning block that comprises anelastic positioning block body and liquid hermetically sealed in theinterior of the positioning block body. In a low temperature, the liquidgets condensed and expanded so as to enlarge the size of the positioningblock body to compensate the size reduction of the light guide plate dueto contraction caused by cooling; and in a high temperature, theelasticity of the positioning block body absorbs the size expansion ofthe light guide plate caused by heating so as to achieve adjustabilityof the LGP positioning block with temperature variation and allow foreffective positioning of the light guide plate, thereby providing theliquid crystal display device with high reliability and stable taste ofdisplayed images. The present invention also provides a method formanufacturing an LGP positioning block of a liquid crystal displaydevice, in which liquid is first filled into the interior of apositioning block body, followed by application and solidification ofthe sealing adhesive to hermetically seal the liquid in the interior ofthe positioning block bod. The LGP positioning block manufactured withsuch a method allows for adjustability with variation of the surroundingtemperature to achieve effective positioning of the light guide plate.

Based on the description given above, those having ordinary skills ofthe art may easily contemplate various changes and modifications of thetechnical solution and technical ideas of the present invention and allthese changes and modifications are considered within the protectionscope of right for the present invention.

What is claimed is:
 1. A method for manufacturing a light guide plate(LGP) positioning block of a liquid crystal display device, comprisingthe following steps: (1) providing a positioning block body that is madeof a material possessing elasticity; and (2) filling and hermeticallysealing a fluid in a receiving compartment formed in an interior of thepositioning block body such that the fluid has a volume defined by thereceiving compartment, wherein the liquid is expandable with a drop oftemperature so as to expand the volume thereof and enlarge a size of thepositioning block body through the elasticity of the positioning blockbody.
 2. The method as claimed in claim 1, wherein positioning blockbody comprises a sealing trough formed by recessing a surface thereof, apassageway in communication with the sealing trough and extending intothe interior of the positioning block body to communicate with areceiving chamber, the fluid being filled through the sealing trough andthe passageway into the receiving compartment, a sealing material beingfilled in the sealing trough to seal the fluid in the receivingcompartment.
 3. The method as claimed in claim 2, wherein the fluidcomprises a liquid.
 4. The method as claimed in claim 3, wherein theliquid comprises distilled water.
 5. The method as claimed in claim 4,wherein the liquid comprising distilled water freezes and expands in atemperature lower than zero degrees Celsius so as to enlarge the size ofthe positioning block body.
 6. The method as claimed in claim 1, whereinthe material that makes the positioning block body comprises rubber. 7.The method as claimed in claim 6, wherein the fluid comprises a liquid.8. The method as claimed in claim 7, wherein the liquid comprisesdistilled water.
 9. The method as claimed in claim 8, wherein the liquidcomprising distilled water freezes and expand in a temperature lowerthan zero degrees Celsius so as to enlarge the size of the positioningblock body.